Function findHeaderIndex

src/installer/targets/toml.ts:128–134

* Locate the byte index of a header line (`[foo.bar]`) when it * appears at the start of a line. Returns -1 if not found.

(content: string, headerLine: string)

 * appears at the start of a line. Returns -1 if not found.
 */
function findHeaderIndex(content: string, headerLine: string): number {
  // Search BOL or right after a newline.
  if (content.startsWith(headerLine)) return 0;
  const needle = '\n' + headerLine;
  const idx = content.indexOf(needle);
  return idx === -1 ? -1 : idx + 1;
}

/**
 * Find the byte index of the next `[...]` or `[[...]]` table header